High Wind Watch 5, NWS Anchorage, AK

021 
WWAK71 PAFC 051257
NPWAER

URGENT - WEATHER MESSAGE
National Weather Service Anchorage AK
357 AM AKST Sun Mar 5 2017

AKZ131-060200-
/O.UPG.PAFC.HW.A.0005.170305T2100Z-170306T2100Z/
/O.NEW.PAFC.HW.W.0004.170305T2200Z-170306T2000Z/
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
357 AM AKST Sun Mar 5 2017

...HIGH WIND WARNING IN EFFECT FROM 1 PM THIS AFTERNOON TO 11 AM
AKST MONDAY...

The National Weather Service in Anchorage has issued a High Wind
Warning, which is in effect from 1 PM this afternoon to 11 AM
AKST Monday. The High Wind Watch is no longer in effect. 

* LOCATION...Valdez to Thompson Pass.

* WIND...North to east 30 to 55 mph with gusts 65 to 80 mph.

* TIMING...Winds will increase and reach warning levels in
  Thompson Pass by early this afternoon. Warning level winds at
  lower elevations may not arrive until the late afternoon to
  early evening hours. Winds should fall below warning levels 
  throughout the area by noon Monday.

* IMPACTS...Travel may be difficult. Trees may be blown over. 
  Loose debris can be moved and damage property.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A high wind warning means a hazardous high wind event is expected
or occurring. People are urged to secure loose objects that could
be blown around or damaged by the wind.

&&

$$

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
406 AM AKST Sat Mar 4 2017

.ANALYSIS AND UPPER LEVELS...

An area of low pressure is located near Shemya and Attu this
morning and is currently pushing a frontal boundary across the
western and central Bering Sea. Gale force wind gusts have been
observed at both Adak and Atka while scatterometer data suggests a
nice swatch of gale force winds extends north and west of Adak
and Atka. The front appears to be shearing apart quite rapidly
early this morning as it begins to clash with high pressure over
the Alaska Mainland/western Bering Sea and upper-level support
looks less than favorable. Warmer air is being advected northward
behind the front as evident at Adak and Atka where temperatures
have warmed into the lower 40s. Ahead of the front will continue
to see periods of light snowfall while behind the front will
continue to see snow transition to rain as warmer air displaces
the colder air.

Over the Alaska mainland, the overall synoptic pattern remains
relatively unchanged. The blocking patter that set-up earlier in
the week still looks rather impressive although there are some
signs that the western half of the blocking pattern might be in
the process of breaking down. Nevertheless, the Alaska mainland
remains under mostly clear skies with sfc based high pressure well
entrenched across the state. The Kuskokwim Delta developed fog
Friday evening and based on forecast soundings, that stratus layer
will be tough to mix out. Gap winds have begun to diminish across
Southcentral Alaska as an area of low pressure in the eastern
Gulf of Alaska weakens. This has allowed the pressure gradient to
relax which will make it increasingly difficult for gap winds to
blow as they have during the past couple of days. The decrease in
winds across Southcentral Alaska has allowed temperatures to drop
further than the past couple of nights. As of this morning, most
locations have seen temperatures in the single digits or below
zero except for the gulf coast where temperatures are in the upper
teens to lower 20s.

&&

.MODEL DISCUSSION...

Models remain in very good agreement through the short-term when
looking at the evolution of the synoptic pattern. However, some
discrepancies are observed tonight into Sunday morning as to how
far the warm front in the Bering Sea moves eastward. Most models
are hinting that the precip stays offshore, which looks like the
most logical solution as high pressure over the state should act
as a deterrent to the front moving too far eastward. Models
continue to indicate a reinforcing shot of cold air dropping south
out of the arctic this weekend. Each model has a different
depiction of how cold the air mass that moves on top of us will
be. However, it is with great certainty that this period of below
normal temperatures will likely persist through the next week.

&&

.AVIATION...
PANC...VFR conditions and light winds will persist.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (through Sunday night)...

Little change is expected in the overall weather pattern through
Sunday night. Pressure gradients will diminish across the North
Gulf Coast today. However, gusty to strong outflow winds will
continue across the Gulf coast, the eastern Kenai Pen, with gales
across the Barren Islands. These conditions should hold through
tonight.

On Sunday, an upper level short wave drops south across
Southcentral and into the Gulf by Sunday evening. In response,
gap flows will increase across much of Southcentral in the
afternoon hours. So except brisk winds through the gaps in the
Alaska Range, Mat Valley, along the Copper River, and of course
the Gulf Coast. The strongest winds look to be once again in the
Valdez and Thompson Pass areas. This event does not look as
strong as the Thu/Fri event, but does bear watching for high wind
potential.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...

There will be little change in the sensible weather pattern as the
region remains under the influence of largely dry northwest flow
aloft. A weak shortwave trough will move over today, bringing
scattered snow showers to the Lower Kuskokwim Valley and Alaska
Range. A warm front in the Bering will also clip Nunivak Island
and will bring accumulating light snow. However, with dry
northwest flow aloft inland, expect inland areas to remain dry
although a few stray snow showers can't be ruled out along the
Delta coast. Slightly colder air and stronger offshore winds will
move in Saturday evening through Sunday night.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...

A rather impressive warm front over the Western and Central Bering
will bring rain (mixed with snow over the Pribilof Islands) as far
east as the Pribilof Islands today before falling apart late
today. A secondary cold front near Shemya will move east toward
Adak before stalling out and becoming a stationary front Saturday
and Sunday. The strongest gale force winds will remain over the
Western and Northern Bering Sea as the tightest pressure gradient
moves north today.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Expect a continuation of conditions of the last week; cold, dry,
and breezy, followed by moderating temperatures and wind by late
next week. Sunday afternoon begins the extended forecast where
the upper pattern looks identical as the one currently overhead. A
trough will continue to sit over the mainland as a ridge amplifies
over the central Bering. The cold outflow pattern will continue as
an arctic air mass gets forced through the coastal mountains,
driving the incredibly gusty winds. There is good agreement within
guidance of a shortwave trough (currently over the pole)
propagating southward over the mainland by late Sunday. The wave
will invigorate the winds around the area, possibly with more
warning level gusts in the Valdez area. Another wave comes through
the flow on Tuesday, enhancing the gradient once again.

A moderation in the pattern comes mid-week when ridging becomes
more established over the Bering Sea. There is discrepancy between
ensemble guidance and deterministic guidance on the nature of the
ridge. Confidence is high in it existing, however, in what shape
is still up in the air. Ensemble mean guidance wants to keep a
more defined ridge and even an omega block in place, while
deterministic guidance wants to beat the ridge down with
shortwaves on the north and eastern periphery. The change in
sensible weather would be a warmer and less windy airmass as
ridging builds in, but still cold/dry. Once these blocks get into
place it's hard to quickly move them out, so I'd put my money on
an established block at this point. Stay tuned.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Heavy Freezing Spray...121 129 130 138 139 185
         Storm...127
         Gale...128 130 131 175 185

&&

SYNOPSIS AND MODEL DISCUSSION...MMC
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA
LONG TERM...MTL